1. Field of Application
This invention relates to pulleys; and more particularly to pulleys for use with conveyor belts.
2. Description of the Prior Art
Pulleys, and especially conveyor belt pulleys constituting the drive or tail pulleys of conveyor belt systems, are subject to many stresses and strains, and a good deal of unsupported bending moments. All of the stresses, strains and bending moments create fatigue in the pulley and many pulleys, currently available on the market for use in belt conveyors, fail during use because the disk or end plate cracks in fatigue and the cylindrical pulley face cracks in fatigue a short distance from where it is welded to the pulley disk.
Some conveyor belt pulleys, such as those shown in U.S. Pat. No. 2,763,158 granted to D. Firth on Sept. 18, 1956 for Conveyor Pulley, and in U.S. Pat. No. 3,134,268 granted on May 26, 1964 to D. Firth for Pulley and Hub Construction, utilize a cylindrical outer shell with radial end walls welded to the outer shell, and hub means to secure the pulley to the shaft by way of connections to the radial end walls. Pulleys of this construction quite often fail in use due to the aformentioned stresses, strains and bending.
Other conveyor pulleys, wherein the end walls are not welded to the cylindrical pulley shell, such as shown in U.S. Pat. No. 2,736,205 granted on Feb. 28, 1956 to M. F. Dunne, Jr. for Pulley and Method of Making Same, in U.S. Pat. No. 3,140,621 granted on July 14, 1964 to G. B. Stone for Pulley Hub with Crowned Outer Face, and in U.S. Pat. No. 3,267,758 granted on Aug. 23, 1966 to W. N. Poundstone for Idler Rollers and Method of Making Same, have resulted in much more highly complex constructions without relieving the failure problems to any appreciable extent. Even such complex fabrications as shown in U.S. Pat. No. 2,767,590 granted on Oct. 23, 1956 to D. C. Currier for Conveyor Pulleys, in U.S. Pat. No. 3,217,554 granted on Nov. 16, 1965 to K. W. Stalkes for Universal Pulley, and in U.S. Pat. No. 3,055,229 granted on Sept. 25, 1962 to F. J. Mecham for Self Cleaning Conveyor Belt Pulley have not resulted in a reliable conveyor belt pulley.
Furthermore pulleys of solid construction, such as shown in U.S. Pat. No. 1,642,989 granted on Sept. 20, 1927 to H. F. Busch for Compressed Core Article and Method of Making Same, and in U.S. Pat. No. 3,711,912 granted on Jan. 23, 1973 to F. Teake et al. for Support Roller for Conveyor Belts and the Like, also fail to provide a beam like composite action pulley.